Sonny Bill Williams has confirmed that he has switched codes and will play for the Sydney Roosters in Australia's National Rugby League next term.

Williams revealed in July that he was poised to quit rugby union and return to rugby league for a spell. And the Roosters have confirmed that he has penned a one-year deal for the 2013 season. Williams said: "I'm looking forward to getting back out there in a game I grew up playing and put my best foot forward."

The 27-year-old was part of the All Blacks' World Cup winning side and also lifted the 2012 Super Rugby title with the Crusaders. He is currently turning out for the Wild Knights in Japan but is sidelined after undergoing surgery on a pectoral muscle. He faces two to four months out but is hopeful that he will be fit for the start of the NRL season in March.

And Williams admitted that it was hard to turn his back on rugby union. "It was pretty tough (to come back). It's tough, but me and Nick (Politis) are good friends, good mates," Williams said. "He tried to get me when I was an 18-year-old. When I made that (handshake) agreement with him I knew it would always be the case.

"This isn't a decision I have made for money - if that was the case, I would be staying with rugby union. I have signed with the club for one season so as to fulfil my pre-existing boxing commitments."